#include <userver/formats/common/items.hpp>

#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <boost/range/adaptor/transformed.hpp>

#include <userver/formats/json/serialize.hpp>
#include <userver/formats/json/value_builder.hpp>

USERVER_NAMESPACE_BEGIN

namespace {

bool IsRvalue(std::string&&) { return true; }

}  // namespace

TEST(FormatsItems, LvalueReference) {
    auto value = formats::json::FromString(R"({"key": "value"})");
    int iterations = 0;
    for (const auto [key, value] : Items(value)) {
        ASSERT_EQ(iterations, 0);
        ASSERT_EQ(key, "key");
        ASSERT_EQ(value.As<std::string>(), "value");

        ++iterations;
    }

    iterations = 0;
    for (auto [key, value] : Items(value)) {
        ASSERT_EQ(iterations, 0);
        ASSERT_EQ(key, "key");
        ASSERT_EQ(value.As<std::string>(), "value");

        ASSERT_TRUE(IsRvalue(std::move(key)));
        ++iterations;
    }
}

TEST(FormatsItems, ConstLvalueReference) {
    /// [Items Example Usage - Simple object]
    const auto value = formats::json::FromString(R"({"key": "value"})");
    int iterations = 0;
    for (const auto& [key, value] : Items(value)) {
        ASSERT_EQ(iterations, 0);
        ASSERT_EQ(key, "key");
        ASSERT_EQ(value.As<std::string>(), "value");

        ++iterations;
    }
    /// [Items Example Usage - Simple object]

    iterations = 0;
    for (auto [key, value] : Items(value)) {
        ASSERT_EQ(iterations, 0);
        ASSERT_EQ(key, "key");
        ASSERT_EQ(value.As<std::string>(), "value");

        ASSERT_TRUE(IsRvalue(std::move(key)));
        ++iterations;
    }
}

TEST(FormatsItems, RvalueReference) {
    auto value = formats::json::FromString(R"({"key": "value"})");
    int iterations = 0;
    for (const auto& [key, value] : Items(std::move(value))) {
        ASSERT_EQ(iterations, 0);
        ASSERT_EQ(key, "key");
        ASSERT_EQ(value.As<std::string>(), "value");

        ++iterations;
    }

    value = formats::json::FromString(R"({"key": "value"})");
    iterations = 0;
    for (auto [key, value] : Items(std::move(value))) {
        ASSERT_EQ(iterations, 0);
        ASSERT_EQ(key, "key");
        ASSERT_EQ(value.As<std::string>(), "value");

        ASSERT_TRUE(IsRvalue(std::move(key)));
    }
}

TEST(FormatsItems, Iterations) {
    auto value = formats::json::FromString(R"({"key1": "v1", "key2": "v2"})");

    auto items = Items(value);
    auto it = items.begin();

    ASSERT_NE(it, items.end());
    auto value_x = *it;
    const std::string key_x = value_x.key;
    auto v_x = value_x.value;

    it++;
    ASSERT_NE(it, items.end());

    auto [key_y, v_y] = *it;

    if (key_x == "key1") {
        ASSERT_EQ(v_x.As<std::string>(), "v1");
        ASSERT_EQ(key_y, "key2");
        ASSERT_EQ(v_y.As<std::string>(), "v2");
    } else {
        ASSERT_EQ(key_x, "key2");
        ASSERT_EQ(v_x.As<std::string>(), "v2");
        ASSERT_EQ(key_y, "key1");
        ASSERT_EQ(v_y.As<std::string>(), "v1");
    }

    ++it;
    ASSERT_EQ(it, items.end());
}

TEST(FormatsItems, BoostRanges) {
    auto value = formats::json::FromString(R"({"key1": "v1", "key2": "v2"})");
    EXPECT_THAT(
        Items(value) | boost::adaptors::transformed(
                           // Must return by value since kv is temporary and stores key.
                           [](auto kv) { return std::move(kv.key); }
                       ),
        testing::UnorderedElementsAreArray({"key1", "key2"})
    );
    EXPECT_THAT(
        Items(value) | boost::adaptors::transformed(
                           // Can return by reference since kv only stores value&.
                           [](auto kv) -> const auto& { return kv.value; }
                       ),
        testing::UnorderedElementsAreArray(
            {formats::json::ValueBuilder{"v1"}.ExtractValue(), formats::json::ValueBuilder{"v2"}.ExtractValue()}
        )
    );
}

USERVER_NAMESPACE_END
